1. Field of the Invention
In general, the present invention relates to a transmission apparatus and a communication network. More particularly, the present invention relates to detection of a period of time with a transmission line affected due to a failure of a power supply occurring in a transmission apparatus. A period of time with a transmission line affected is a period of time during which a line transmission is affected by a failure of a power supply occurring in a transmission apparatus.
2. Description of the Related Art
When a failure of a power supply occurs in a transmission apparatus employed in a communication network, the transmission apparatus in which the failure of a power supply occurs becomes as a cause of disabled communication in another transmission apparatus communicating with the transmission apparatus including the failing power supply. It should be noted that another transmission apparatus communicating with the transmission apparatus including the failing power supply is also referred to hereafter as an adjacent transmission apparatus. As the power supply is recovered, however, the normal communication is also restored as well. A period of time during which the communication in the transmission apparatuses is not functional due to the failure of a power supply is reported by a center of the communication network to users. As described above, such a period of time is referred to as a period of time with a transmission line affected. In the conventional system, when a failure of a power supply occurs in a transmission apparatus, the fact that an adjacent transmission apparatus becomes incapable of receiving a signal from the failing transmission apparatus is detected by an alarm unit which then transmits alarm information to a monitor/control unit. Then, the alarm information is recorded in a history recording unit. Subsequently, the alarm unit reports the alarm information to a center through a monitoring LAN. The center carries out activities such as general tests, monitoring, restoration tests and line setting of the transmission apparatuses. As the failure of a power supply occurring in the transmission apparatus is fixed, pieces of alarm information collected by the center from transmission apparatuses adjacent to the failing transmission apparatus are output to a printer to indicate how long communication lines have been affected by the failure of a power supply. A person in charge of system maintenance and system supervision then visually examines the pieces of alarm information one piece after another to asses the effects of the failure of the power supply.
However, the conventional transmission apparatus has the following problems.
(1) When a failure of a power supply occurs in a transmission apparatus, each communication line connected to the apparatus is affected till the failure is fixed and the apparatus is restored to a normal state. In a multi-vendor environment involving several vendors supplying software and hardware as well as several vendors doing communication businesses, it is quite within the bounds of possibility that alarm information varies from vendor to vendor. It is thus necessary for the person in charge of maintenance to examine periods of time each with a transmission line affected due to a failure of a power supply occurring in a transmission apparatus one time after another by taking differences in alarm information between vendors into consideration. Such examination requires a long time and it is thus difficult to present a period of time with a transmission line affected to users immediately. In addition, a large-scale communication network normally has a hierarchical structure wherein a plurality of transmission apparatuses connected to a transmission apparatus with,a failing power supply may be centrally monitored by different centers. In this case, each of the centers detects a period of time with a transmission line affected by the transmission apparatus in which the failure of a power supply has occurred. In order to grasp the whole picture of the state, however, it is necessary to collect all periods of time each with a transmission line affected which are detected by a plurality of centers and it thus takes an even longer time to collect such pieces of information. In addition, the person in charge of maintenance has to identify all transmission apparatuses adjacent to the transmission apparatus in which the failure of a power supply has occurred and detect periods of time each with a transmission line affected from pieces of alarm information received from the adjacent transmission apparatuses in order to examine the periods of time each with a transmission line affected. Due to the fact that each of the centers control s a large number of transmission apparatuses, however, it is difficult to manually and in a short time form a judgment as to which transmission apparatuses are involved in communications with the transmission apparatus in which the failure of a power supply has occurred, and the formation of such a judgment thus entails a number of people in charge of maintenance and a long time.
(2) When the failure of a power supply is fixed, the transmission apparatus in which the failure of a power supply has occurred informs a center that the power supply has been recovered and transfers data such as line-setting information from a non-volatile backup memory of the transmission apparatus to a volatile memory of the apparatus to set the state prior to the occurrence of the failure of a power supply before resuming communication. At that time, a secondary failure may occur because of some reasons so that complete line setting becomes impossible. For example, the loading (the transfer) of line-setting information from the non-volatile backup memory to the volatile memory ends in a failure for some lines. In this case, nevertheless, the transmission apparatus in which a failure of a power supply has occurred appears to the center to have been restored to the normal operation by the recovery of the power supply of the transmission apparatus. In actuality, however, an adjacent transmission apparatus connected to a line of which can not be set normally, is still in a state of being incapable of receiving a signal as before. As a result, the adjacent transmission apparatus continues transmitting alarm information to the center. At that time, the person in charge of maintenance needs to identify and fix the secondary failure on the basis of the alarm information. Since the transmission apparatus with the recovered power supply itself does not transmit alarm information, however, it may take time to identify the secondary failure. In addition, in case the power-supply of a transmission apparatus is interrupted during line setting of the transmission apparatus by a center, line-setting information to be transmitted from the center to transmission apparatuses is not reflected in the failing transmission apparatus, but is reflected in the adjacent transmission apparatus. On the other hand, when a transmission apparatus in which a failure of the power supply has occurred resets the connecting lines after the power supply is recovered, no signal is transmitted to an adjacent transmission apparatus, a transmission line of which remains to be set. As a result, the adjacent transmission apparatus is left in a state of being incapable of receiving signals. It is thus naturally desirable to improve the method of recovering the communication network through reduction of the time loss incurred in the recovery by letting the center naturally see alarm information received from a transmission apparatus in which a secondary failure of a power supply has occurred, causing the transmission apparatus incapable of normally setting lines.
It is thus an object of the present invention to provide a transmission apparatus and a communication network that are capable of detecting periods of time each with a transmission line affected in a short time.
It is another object of the present invention to provide a transmission apparatus and a communication network that are capable of fixing a secondary failure in a short period of time even if the secondary failure occurs in a transmission apparatus with its power supply recovered.
In accordance with an aspect of the present invention, there is provided a transmission apparatus characterized in that the apparatus comprises:
a power-supply unit;
first detection means for detecting a power-supply recovery of the power-supply unit;
request means which is used for transmitting a demanding command to an adjacent transmission apparatus completing line setting based on line-setting information to request the adjacent apparatus to transmit alarm information when the first detection means detects a power-supply recovery, wherein the alarm information includes a disabled-reception time and a recovered-reception time, that is, times at which reception of signals from the transmission apparatus is disabled and recovered respectively;
first reception means for receiving the alarm information from the adjacent transmission apparatus; and
second detection means for detecting a period of time with a transmission line affected between a disabled-reception time and a recovered-reception time of the adjacent transmission apparatus based on the alarm information received by the first reception means.
It is desirable to again transmit the demanding command to the adjacent transmission apparatus which has been subjected to the line setting based on the line-setting information after again carrying out the line setting of the adjacent transmission apparatus in case the alarm information received earlier indicates that the reception of the adjacent transmission apparatus has not been recovered yet. It is further desirable to provide the transmission apparatus with:
third detection means for detecting whether or not communication with the adjacent transmission apparatus which has been subjected to the line setting based on the line-setting information is possible;
recording means for recording alarm information based on a result of detection produced by the third detection means into a history file wherein the alarm information includes times at which reception of a signal from the adjacent transmission apparatus is disabled and recovered;
second reception means for receiving an incoming demanding command from an adjacent transmission apparatus which has been subjected to the line setting based on the line-setting information; and
transmission means for obtaining pieces of alarm information for the adjacent transmission apparatus transmitting the incoming demanding command from the history file and transmitting the pieces of alarm information to the adjacent transmission apparatus transmitting the incoming demanding command in response to the incoming demanding command.
According to the configurations described above, the request means transmits a demanding command to an adjacent transmission apparatus completing line setting based on line-setting information to request the adjacent apparatus to transmit alarm information when the first detection means detects a power-supply recovery. The second reception means of the adjacent transmission apparatus receives the demanding command. The transmission means of the adjacent transmission apparatus obtains alarm information for the transmission apparatus transmitting the demanding command and transmits the alarm information to the transmission apparatus transmitting the demanding command. The first reception means of the failing transmission apparatus receives alarm information. The second detection means of the failing transmission apparatus detects a period of time with a transmission line affected from the alarm information. The period of time with a transmission line affected is then transmitted typically to a center. In this way, a period of time with a transmission line affected can be detected in a short time. In addition, in the event of a secondary failure, a demanding command is retransmitted after again carrying out the line setting based on the line-setting information. As a result, an automatic recovery is possible even if a secondary failure occurs.
In accordance with another aspect of the present invention, there is provided a communication network comprising a center and a plurality of transmission apparatuses each connected to the center by a communication line, the communication network characterized in that:
each of the transmission apparatuses comprises:
a power-supply unit;
first detection means for detecting a power-supply recovery of the power-supply unit;
request means which is used for transmitting a demanding command to an adjacent transmission apparatus completing line setting based on line-setting information to request the adjacent apparatus to transmit alarm information related to the transmission apparatus transmitting the demanding command, when the first detection means detects a power-supply recovery, wherein the alarm information includes a disabled-reception time and a recovered-reception time, that is, times at which reception of signals from the transmission apparatus is disabled and recovered respectively;
first reception means for receiving the alarm information from the adjacent transmission apparatus;
second detection means for detecting a period of time with a transmission line affected between a disabled-reception time and a recovered-reception time of the adjacent transmission apparatus included in the alarm information received by the first reception means;
transmission means which is used for transmitting the periods of time each with a transmission line affected to the center when all of the alarm information indicating that all adjacent transmission apparatuses have recovered is received; and
second reception means for receiving line-setting information from the center, whereas
the center comprises:
recording means for recording line-setting information for the transmission apparatuses; and
second transmission means for transmitting the line-setting information to the transmission apparatus transmitting the periods of time each with a transmission line affected if the periods of time each with a transmission line affected for all adjacent transmission lines completing line setting based on the line-setting information recorded by the recording means have not been detected.
According to the configurations described above, a transmission apparatus in which a failure has occurred detects a period of time with a transmission line affected of each adjacent transmission apparatus as is the case with the one described above. When the reception capabilities of all the adjacent transmission apparatuses are recovered, allowing periods of time each with a transmission line affected to be detected, the periods of time each with a transmission line affected are reported to the center. If the center has not received a period of time with a transmission line affected of a transmission apparatus which is adjacent to the transmission apparatus experiencing a failure of a power supply and supposed to have undergone line setting based on line-setting information stored in the center, the center transmits the line-setting information to the transmission apparatus occurring the failure of a power supply. The transmission apparatus occurring a failure of a power supply again carries out line setting based on the line-setting information received from the center. In this way, an automatic recovery is possible even if a power-supply occurs during line setting.